Can an undiagnosed brain tumor cause tingling sensations in a patient with a history of Selective Serotonin Reuptake Inhibitor (SSRI) discontinuation syndrome and prediabetes, presenting with symptoms in their lower legs, arms, and back?

Can a Brain Tumor Cause Tingling in Lower Legs, Arms, and Back?

A brain tumor is an unlikely cause of isolated tingling sensations in the lower legs, arms, and back, especially in a patient with prediabetes and recent SSRI discontinuation—these alternative diagnoses are far more probable and should be evaluated first.

Why Brain Tumors Are Unlikely to Present This Way

Typical Brain Tumor Presentations

Brain tumors typically cause multifocal neurological symptoms that include headache (present in nearly 90% of cases), nausea, vomiting, mental changes, gait difficulties, cranial nerve palsies, and focal neurological deficits 1. The pattern you describe—bilateral tingling in extremities and back—does not fit the classic presentation of primary brain tumors.

Leptomeningeal Metastases: A Rare Exception

The only brain-related malignancy that could theoretically cause your symptom pattern would be leptomeningeal metastases (carcinomatosis), which can present with:

• Radicular signs including weakness and sensorimotor deficits of extremities 1
• Focal or irradiating neck and back pain 1
• Multiple levels of nervous system involvement simultaneously 1

However, leptomeningeal disease would typically also include headache, cranial nerve palsies, mental changes, and occurs almost exclusively in patients with known cancer 1. This is not a presentation of undiagnosed brain tumors in otherwise healthy individuals.

Far More Likely Diagnoses in Your Case

Prediabetic Neuropathy (Most Likely)

Your prediabetes is the most probable cause of your tingling sensations. Prediabetic neuropathy:

• Affects a substantial proportion of subjects with prediabetes 2
• Mainly affects small fibers mediating sensory function 2
• Causes symptoms that are generally milder than diabetic neuropathy 2
• Commonly presents as uncomfortable tingling (paresthesia) in the feet and legs, which can progress up the limbs 1
• Can involve upper limbs (hands) as the condition progresses 1

The pattern of tingling in lower legs, arms, and back is consistent with a length-dependent peripheral neuropathy, which is the hallmark of metabolic neuropathies like prediabetes 1, 2.

SSRI Discontinuation Syndrome (Contributing Factor)

Your recent SSRI discontinuation could be contributing to or exacerbating your symptoms:

• SSRI withdrawal symptoms can include paresthesias and sensory disturbances 3
• Symptoms typically occur within a few days of drug discontinuation 3
• The syndrome can last several weeks even with gradual tapering 3
• Symptoms may have late onset or longer persistence 3

Red Flags That Would Suggest Brain Pathology

You should seek urgent neurological evaluation if you develop any of these symptoms:

Concerning Neurological Signs

• Headaches that are rapidly increasing in frequency, awakening you from sleep, or worsened by Valsalva maneuver 4
• Visual changes including double vision, visual field defects, or papilledema 1, 4
• Mental status changes including confusion, personality changes, or cognitive decline 1
• Gait difficulties or balance problems beyond what tingling alone would cause 1
• Focal weakness (hemiparesis) or unilateral sensory loss 4
• Cranial nerve palsies causing diplopia, hearing loss, or facial weakness 1
• Bowel or bladder dysfunction suggesting cauda equina syndrome 1

Critical Point

Any abnormal neurological finding significantly increases the likelihood of clinically significant intracranial pathology and warrants further investigation 4. However, isolated sensory symptoms (tingling) without these red flags do not suggest brain tumor.

Recommended Diagnostic Approach

First-Line Evaluation

1. Check hemoglobin A1c and fasting glucose to assess glycemic control 1, 2
2. Evaluate for metabolic syndrome components including dyslipidemia, which contributes to prediabetic neuropathy 2
3. Detailed neurological examination focusing on:
   • Sensory testing in a stocking-glove distribution 1
   • Vibration and proprioception testing 1
   • Reflexes (often reduced in peripheral neuropathy) 1

When to Consider Neuroimaging

Brain MRI would only be indicated if you develop:

• Progressive focal neurological deficits 4
• Severe headaches with concerning features 4
• Mental status changes 4
• Signs of elevated intracranial pressure 4

MRI is NOT indicated for isolated bilateral tingling in extremities without other neurological signs 4.

Management Strategy

Address the Most Likely Causes First

For prediabetic neuropathy:

• Achieve normoglycemia through lifestyle modification and possibly metformin 2
• Correct cardiovascular risk factors including dyslipidemia 2
• Consider symptomatic treatment with duloxetine, gabapentin, or pregabalin if tingling is painful or disabling 1

For SSRI discontinuation:

• Symptoms typically resolve within weeks 3
• If severe, consider brief reinstitution of SSRI followed by slower taper 3

Common Pitfall to Avoid

Do not pursue extensive neuroimaging for isolated sensory symptoms in the setting of prediabetes and recent SSRI discontinuation. This leads to unnecessary testing, incidental findings, anxiety, and delays in treating the actual cause 4. Focus on metabolic optimization and symptom management first.